Recently, there has been great advancement in production of miniature and lightweight electronic apparatuses such as mobile telephones and personal computers. In accordance therewith, such apparatuses having movable housings arranged to be opened and closed with respect to fixed housings, i.e., folding type apparatuses, are increasing in number. A folding device used for such apparatuses is required to be low in cost and easy to use.
Such conventional folding device and a method of mounting the same will be described with reference to FIG. 3 and FIG. 7 to FIG. 9.
In a sectional view of the drawings, the dimension is shown elongated in the radial direction to make easy the understanding of the relationship between a fixed cam and a movable cam.
FIG. 7 and FIG. 8 are a sectional view and an exploded view in perspective of a conventional folding device.
Metal fixed member 1 in a substantially cylindrical shape is provided with fixed cam 2 on a periphery of its right-hand side face. Fixed cam 2 comprises protruded portion 2A and two sloped portions 2B and 2C extending upwardly and downwardly from protruded portion 2A.
Further, metal movable member 3, which is also in a substantially cylindrical shape, is arranged for rotation in an opening and closing direction with respect to fixed member 1. Movable member 3 is provided with movable cam 4 on a periphery of its left-hand side face (as shown in FIG. 7) in confronting relation with fixed cam 2.
Movable case 5, which is in a substantially cylindrical shape and made of sintered alloy, is provided with convex wall portion 5A sticking outward on its outer periphery and guide groove 5B on its inner periphery. Protrusion 3A provided on the outer periphery of movable member 3 is inserted into guide groove 5B so that movable member 3 is held for movement in an axial direction.
Further, coil spring 6 is mounted so as to be weakly pre-compressed in a space between a right-hand side face of movable member 3 and a right-hand bottom face of movable case 5. Spring 6 urges movable member 3 leftward, and thereby, a tip end of movable cam 4 is held in resilient contact with sloped portion 2B of fixed cam 2.
Fixed case 8, which is in a substantially cylindrical shape, and fixed member 1 are fixed to a left end portion of fixed shaft 7 which has a substantially circular pillar shape. Moreover, a right end portion of fixed shaft 7 passes through a hollow portion of movable member 3 and spring 6 to be rotatably mounted to a right-hand face of movable case 5 by means of locking ring 9.
Fixed case 8, provided on its outer periphery with convex wall portion 8A, is rotatably mounted to a left-hand side face of movable case 5 by means of fixed shaft 7.
Folding device 10 is thus constructed with fixed member 1, movable member 3, spring 6 and the like housed in movable case 5.
Fixed case 8 of folding device 10 is fixed to fixed housing 12 while movable case 5 is fixed to movable housing 13, respectively, as shown in the perspective view of a mobile telephone of FIG. 3, for example. On the upper side of fixed housing 12, there are formed operating portion 12A made up of a plurality of keys and voice input portion 12B made up of such members as a microphone. Display portion 13A formed of an LCD and the like and voice output portion 13B formed of a speaker and the like are formed on a surface of movable housing 13.
An arrow in FIG. 3 shows an opening and closing operation of movable housing 13.
Thus, the electronic apparatus is constructed by having movable housing 13 hingedly supported by folding device 10 for opening and closing with respect to fixed housing 12.
Such folding device 10 is mounted in the manner shown in a sectional view of FIG. 9. First, fixed case 8 and movable case 5 are inserted in insertion holes of fixed housing 12 and movable housing 13 so as to prevent fixed case 8 and movable case 5 from respectively rotating by means of convex wall portions 5A and 8A. A cap 14 is then mounted to a left-hand side face of fixed housing 12 to fixedly attach the folding device 10 for assembling so that the folding device 10 will not come out in the axial direction.
In the above structure, spring 6 urges movable member 3 to rotate downward, that is, in a closing direction when the tip end of movable cam 4 is in resilient contact with sloped portion 2B provided on the lower part of fixed cam 2, as shown in FIG. 7.
Accordingly, movable housing 13 to which movable case 5 is fixed is held to be closed with respect to fixed housing 12.
In such a closing state, when movable housing 13 is opened by means of a hand, movable member 3 having protrusion 3A inserted in guide groove 5B moves toward the right in movable case 5 and rotates upward through movable case 5 fixed to movable housing 13. The tip end of movable cam 4 is then in resilient contact with upper sloped portion 2C over protruded portion 2A of fixed cam 2, so that movable member 3 is urged upward, that is, in an opening direction. Movable housing 13 is thus opened.
That is to say, rotation of movable case 5 fixed to movable housing 13 allows movable member 3 to move in the axial direction, so that the tip end of movable cam 4 is in resilient contact with one of sloped portions 2B and 2C of fixed cam 2.
An opening and closing operation of movable housing 13 with respect to fixed housing 12 is arranged as described above. An example of such a folding device is disclosed in Japanese Laid-open Patent Publication No. 2002-89542.
In the conventional folding device, however, cap 14 is used for mounting after inserting folding device 10 into fixed housing 12 or movable housing 13 of an electronic apparatus, so that there are problems that components are large in number and mounting to an apparatus is troublesome.
The invention is to solve such conventional problems and to provide a folding device, which comprises a fewer number of components and which is capable of easy mounting to an apparatus, and a method of mounting the same.